Gardens - Fruit & Vegetable Gardening

Learn to grow a sweet potato

You don't usually equate the sweet potato with terms of endearment, but singer-songwriter James Taylor does just that when he refers to his girlfriend—who's responsible for the divine happiness he feels one particular day—as Sweet Potato Pie in his appropriately titled song “Sweet Potato Pie.” I fully understand: sweet potatoes (Ipomoea batatas) are sublime, not only with respect to taste and cooking versatility, but in nutritional value as well.

These healthful superstars are an excellent source of vitamin A (in the form of beta carotene, which also offers antioxidant properties) and a good source of vitamin C, not to mention the dietary fibre and vitamin B6 they provide. And great news: if your region has at least a 100-day frost-free season, you can likely grow them, as an increasing number of Canadian gardeners have discovered. Short-season cultivars (90 to 100 days) such as ‘Georgia Jet' and Tainung 65 thrive in home gardens across the country, especially during dry, hot summers. (One gardener in Northampton, New Brunswick, raised a 3.4-kilogram Tainung 65 monster a couple of years ago.) But while they like it hot, sweet potatoes are no prima donnas. They require little watering, weeding or feeding, and they store well.

Planting your slipsAlthough members of the morning glory family (Convolvulaceae), sweet potatoes are not sown from seed, but rather from slips, small shoots that grow from the tuber that are then transplanted. While slips are not readily available at garden centres, there are a few Canadian suppliers you can order from—or you can grow your own (see below).

Sweets can't tolerate frost, so you should plant your slips about the same time you normally transplant warm-temperature veggies such as peppers and eggplants. Harden off as you would other tender plants.How to grow your own slipsStick toothpicks around the middle of a sweet potato and suspend it in a jar (or sturdy glass) of water, submerging the bottom half of the tuber (the end with remnants of previous stems—often the wider end, depending on the veggie's shape—should point up). After about a month, you should have several slips about 20 centimetres long. Remove them with a knife or simply by giving them a twist.

Another way to grow slips is to place several sweet potatoes in a bed of sand covered with a moist layer of more sand five centi­metres thick. Once the shoots start to grow, add an additional 2.5 centimetres of sand, keeping it moist but not waterlogged and between 15 and 27°C. Slips should reach 20 centimetres in about six weeks.

(Keep in mind, however, that supermarket-bought sweet potatoes may not produce slips if they have been kept in cold storage—below 10°C.)